Within the context of a program directed at determination of the specific actions of insulin, glucocorticoids and prolactin in the regulation of mammary metabolism; and, at evaluation of the metabolic changes occurring in extramammary tissues during lactation and the regulation of these, a series of studies will be undertaken as follows: 1. Evaluation of possible relationships between hormone actions on the cAMP system and their actions upon mammary metabolism. 2. Identification of hormonal (or other) actions upon liver and adipose tissue which alter metabolic patterns and hormone responses during lactation. 3. Evaluate further effects of diet composition on the maintenance requirements and partial efficiencies of synthesis of milk components.